Solar cells are a very attractive source of clean energy. CuIn1-xGaxSe2 (CIGS) has the potential to become a major candidate in this field. Its large optical absorption coefficient, which results from a direct energy gap, permits the use of thin layers (1-2 μm) of active material. CIGS solar cells are also known for their long-term stability. Currently, a great deal of effort is being expended to develop low-cost technologies for fabricating CIGS thin films, using several techniques, including vacuum deposition technology such as physical vapor deposition and sputtering, and non-vacuum technologies such as electrodeposition, nano-particles-based deposition, ink jet printing and electroless deposition. Physical vapor deposition (PVD) is an excellent tool for understanding film growth and for developing models, but it is challenging to scale up for commercial production because of film non-uniformity and low material utilization. Sputtering techniques are suitable for large-area deposition, but they require expensive vacuum equipment and sputtering targets.
A non-vacuum electrodeposition technique has the potential to prepare large-area uniform precursor films using low-cost source materials and low-cost capital equipment. Electroplating is a potentially suitable preparation method to obtain low-cost precursor films. The electrodeposition process could provide: (a) high-quality film with very low capital investment; (b) a low-cost, high-rate process; (c) use of very low-cost starting materials (e.g., low-purity salts, solvents), based on automatic purification of the deposited materials during plating; (d) a large-area, continuous, multi-component, low-temperature deposition method; (e) deposition of films on a variety of shapes and forms (wires, tapes, coils, and cylinders); (f) controlled deposition rates and effective material use (as high as 98%); and (g) minimum waste generation (i.e., solution can be recycled). Therefore, the electrodeposition technique has been attractive for growing CIGS layers for photovoltaic applications. It is of general interest in this field to obtain high-efficiency electrodeposited CIGS solar cell devices without requiring the use of any PVD step.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.